Filter device

ABSTRACT

The invention relates to a filter device, in particular for lubri¬cating oil filtration, comprising at least two filter inserts ( 27 ), in each of which a filter material ( 43 ) is accommodated, which are provided with fluid passage points ( 37, 39 ) and can be stacked on top of one another with the formation of a stack, and further comprising a back-flushing device ( 55,57 ) which is movably arranged along the inner side of the filter inserts ( 27 ). The invention is characterized in that the individual filter inserts ( 27 ) are designed as identical parts at least with respect to their housings.

The invention relates to a filter device, in particular for the filtration of lubricating oil, consisting of at least two filter inserts, in each of which a filter material is disposed, which are provided with fluid passage points and which can be stacked on top of one another, thereby forming a stacked structure, and comprising a backwash device, which is displaceably arranged along the inside of the filter inserts.

The integrity of lubricating oil is very important for the operational reliability and durability of internal combustion engines. In particular the continuous operation of diesel engines, which are operated using heavy oil, for instance in marine applications, puts particularly high demands on the condition of the lubricating oil, i.e. in such applications the use of filter devices for the purification of lubricating oil is essential. In this regard the prior art specifies that filter devices are used in which filter inserts can be backwashed in order to permit longer time periods between the replacement of filter inserts, to keep maintenance costs low. Document DE 20 2016 003 089 U shows a filter device of the type described above as an example of the corresponding prior art.

Based on this prior art, the invention addresses the problem of providing a filter device of the type mentioned above, which can be produced in a particularly simple and cost-effective manner.

According to the invention, this problem is solved by a filter device having the features of Claim 1 in its entirety.

According to the characterizing part of Claim 1, an essential feature of the invention is that the individual filter inserts are formed as identical parts at least with respect to their housing. By means of injection molding, in particular from plastic materials, it is possible to produce identical parts in an economical manner at low production costs thanks to the elimination of the cost for different molding tools. This results in low acquisition costs for the filter device and low maintenance costs associated with filter replacement and thus low total operating costs. Cost-effective plastic materials such as polyamides, for example PA6, can be used as housing materials, optionally with an oil-proof coating.

In advantageous exemplary embodiments, the housing of the filter inserts has an annular body at each of its free face sides.

At least one projecting annular rib can advantageously be provided on the annular body on the one free face side of a filter insert, which annular rib engages with an associated annular recess in the annular body on the other face side of a downstream filter insert, thereby forming the stacked structure. The stacked structure can thus be formed at low assembly costs as an integral component made of filter inserts because the engagement of the relevant annular rib with the corresponding recess ensures the reciprocal centering of the filter inserts without special measures. Furthermore, the filter inserts can be connected to one another in a simple manner by gluing, wherein the adhesive is introduced into the relevant recess before the filter elements are assembled, for example in the form of a two-component glue.

In advantageous exemplary embodiments, the relevant annular rib is subdivided into rib parts by at least one interruption forming a gap, with at least one projection engaging with a gap of the annular rib being provided in the downstream filter insert in the stacked structure in the annular recess. In addition to the reciprocal centering, a form-fitting anti-twist protection is thus also formed between the filter inserts. The arrangement can in particular be such that the one free face side of each filter insert has the relevant annular rib having the at least one intermediate gap and correspondingly the other free face side has the respective annular recess having the projection located therein.

In particularly advantageous exemplary embodiments, the face sides of the filter inserts facing away from one another arranged in the stacked structure each have a cover part, which are designed as identical parts. These too can be manufactured from the above-mentioned plastic material by means of injection molding in an economical manner and, due to their design as identical parts; they can be produced at low molding tool costs.

At least one part of the cover parts is advantageously fluid-permeable, such that the flow path to the inside of the filter inserts is kept free for the filtering.

In particularly advantageous exemplary embodiments, the arrangement is such that the annular body of the housings of the filter inserts, one of which has the annular recess and the other of which has the rib part, are connected to one another via inner and outer longitudinally extending frame parts, which delimit window-like fluid passage points, and wherein a filter medium is accommodated in the space between inner and outer frame parts. Said filter medium is preferably a single- or multi-layer, pleated filter mat track having a metallic supporting mesh on the outside on both sides. The fluid passage points are used to pass the filter medium preferably from the inside to the outside during filtration.

For every filter insert, the backwash device has a motor-drivable backwasher arm which, formed in the manner of a slot nozzle, travels along the fluid passage points formed on the inner frame parts by means of a drive shaft which, formed hollow, serves to remove backwash from the device. Ambient pressure may be present at the hollow shaft, for the operational system pressure of the filter device to generate the volume flow of the backwash volume, or a vacuum may be present in the hollow shaft due to a connected suction device.

In particularly advantageous exemplary embodiments, the individual slot nozzles of the backwasher arm are axially offset relative to one another and by a rotation angle such that at least one slot nozzle is located above a window-like fluid passage point and at least one additional, preferably adjacent slot nozzle is simultaneously disposed over a frame part next to another passage point. In this arrangement, the unblocking of a relevant passage window by a washer arm is linked to the blocking of another passage window by the other washer arm and vice versa, in this way the formation of pulsations in the backwash volume is minimized.

The adjacent inner longitudinal frame parts can be slanted relative to the radial direction, so that they define a flow direction for every passage window of each filter insert, which is slanted by a specified angle relative to the inflow direction of the opening of the relevant slot nozzle. This results in a slanted flow path through the filter medium furthering the removal of contamination.

The arrangement can furthermore advantageously be such that the relevant slot nozzle expands starting from the inner side of the filter insert assignable thereto towards the hollow drive shaft. The flow cross section at the slot nozzle itself, tapered in comparison, produces a Venturi effect with locally increased flow speed in the effective area of the washer arm, which results in an increased backwash effect with a reduced washing volume.

In particularly advantageous exemplary embodiments, the backwasher arm for each filter insert consists of identical components, which are connected to each other by a tongue and groove connection at their face side, comparable to that of the filter inserts. The design as identical parts makes for reduced production costs for the entire device.

As an additional filter insert in the layer structure, one having at least one spring-loaded bypass valve can be used, to prevent the risk of interruption of the lubricating oil supply in the case of blocked filter inserts.

In exemplary embodiments, in which at least all filter inserts are glued to one another on their face sides which are adjacent to each other, thereby forming the layer structure, and are thus connected to one another in an undetachable manner, the layer structure can be inserted and exchanged as a total package. The layer structure with the filter inserts can be removably installed in a filter housing, which has a fluid inlet for unfiltered fluid, a fluid outlet for filtered fluid and an outlet for the backwash.

The invention is explained in detail below with reference to exemplary embodiments depicted in the drawings, in which:

FIG. 1 shows a central longitudinal section of an exemplary embodiment of the filter device according to the invention;

FIG. 2 shows a perspective oblique view of the backwash filter assembly of the exemplary embodiment of FIG. 1, depicted on a larger scale compared to FIG. 1 and cut away along a centrally located central plane;

FIG. 3 shows a perspective oblique view of a separately depicted filter insert of the assembly, viewed from the top;

FIG. 4 shows a depiction, corresponding to FIG. 3, of the filter insert, viewed from the bottom;

FIG. 5 shows an enlarged partial cross section of the area of a filter insert adjacent to the slot nozzle of a washer arm, wherein the slot nozzle is shown in a position aligned with an inner longitudinal frame part of the filter insert;

FIG. 6 shows a partial cross section corresponding to FIG. 5, wherein the slot nozzle is oriented at a fluid passage point between interior longitudinal frame parts: and

FIG. 7 shows a central longitudinal section of a second exemplary embodiment of the filter device according to the invention.

FIG. 1 shows an exemplary embodiment of the filter device according to the invention having a filter housing designated as a whole by 1, which has a cup-shaped main housing part 3, at the base 5 of which a bearing point 7 is located coaxial to a central housing longitudinal axis 6. By way of access to the housing chamber 9 adjacent to the base 5 a side inlet 11 for the supply of unfiltered fluid is provided, the housing chamber 9 forming the dirty side. At the top, the main housing part 3 is closed by means of a housing cover 15 mounted in a removable manner by means of retaining screws 13, in which housing cover a bearing point 17 coaxial to the axis 6 is formed, just like in the base 5. In the main housing part 3, a filtered fluid outlet 19 is provided in the region of the housing cover 15, which filtered fluid outlet is arranged in a position aligned with the inlet 11 and which outflows over the filtered fluid from the adjacent housing chamber 21, which forms the clean side during operation. In the main housing part 3, above a wall shoulder 23 forming a step, which is located in the vicinity of the unfiltered fluid inlet 11, a backwash filter assembly which is identified as a whole with the reference numeral 25 is arranged, which is depicted separated in FIG. 2.

The assembly 25 has a stacked structure of filter inserts. Two filter inserts 27 are provided in the depicted exemplary embodiment, which filters are formed as identical parts and which are shown in FIGS. 3 and 4 in individual depictions. The circular cylindrical housing of the filter inserts 27 has, at every free face side, a first annular body 29 and a second annular body 31, of which the first annular body 29 can be seen at the top in FIG. 3 and the second annular body 31 can be seen at the top in FIG. 4. A ring of inner frame parts 33 and a ring of outer frame parts 35 extend between the annular bodies 29, 31, which, for the sake of clarity, are not all numbered n the figures. The frame parts 33 and 35 extend at regular distances from one another parallel to the axis 6 of the circular cylindrical housing and leave open inner fluid passage points 37 and outer fluid passage points 39 between them, which extend in a continuous manner slot-like between the frame parts 33, 35 and of which only part is numbered. The filter medium 43 is located in the chamber 41, cf. FIGS. 5 and 6. It consists of a pleated filter mat track made up of at least one filter layer, on the two outer sides of which there is a supporting layer in the form of a mesh structure. In advantageous examples, the filter fineness is in the range from 25 to 34 μm. The outer and inner frame parts 33 and 35 extend away from the annular bodies 29, 31 each across half the axial length of the housing. During its assembly, the filter medium 43 is inserted into the chamber 41 of a housing half, whereupon the housing halves are pieced together and the frame parts 33 and 35 are butt joined to one another at the relevant joint 45 by means of welding or gluing.

The filter inserts 27 have, as FIGS. 3 and 4 most clearly show, an annular rib on the face side of the first annular body 29 concentric to the cylinder axis and axially projecting and having a rectangular cross section, which annular rib is subdivided, by means of three interruptions, each of which forms a gap 47 of equal length, into three annular rib parts 49, which are likewise of equal length. On the opposite face side in the second annular body 31, which is visible at the top in FIG. 4, a recess 51 is formed, complementing the annular rib parts 49 and which has the form of a sunk annular groove, in which, corresponding to the gaps 47 located between the annular rib parts 49 of the other annular body 29, projections 53 are formed. When the filter inserts 27 are pieced together to form a stacked structure, this produces a form-fitting, corresponding engagement of the annular rib parts 49 with the recess 51 of the annular body 31, with simultaneous engagement of the projections 53 in the gaps 47 on the annular body 29. The filter inserts 27 are thus not only centered relative to one another, but are also secured against twisting. The filter inserts 27 can be easily connected to one another to form a non-detachable structure, in that before the assembly a glue, preferably a two-component glue, is introduced into the recess 51.

FIG. 2 shows the backwash filter assembly 25 formed of a stacked structure having two filter inserts 27. As depicted, each filter insert 27 has an inner backwash device, having a coaxial hollow shaft 55, on which a washer arm 57 is located. They radially extend from the hollow shaft 55 to the immediate vicinity of the inner circumference of the inner frame parts 33, cf. FIGS. 5 and 6, and form, starting from an inflow point 59 on the hollow shaft 55, a narrow fluid path, which ends in a slot nozzle 61, cf. FIGS. 5 and 6. The slot nozzles 61 extend across the entire axial length of the inner fluid passage points 37. A hollow shaft end part 63 adjoins the hollow shaft 55 of the bottom washer arm 57, which hollow shaft end part is routed to the backwash outlet 65 on the base 5 of the filter housing 1, where the hollow shaft end part 63 is, in the case of an assembly 25 installed in the filter housing 1, rotatably mounted at the bearing point 7 and is sealed there by means of a shaft ring 67. The hollow shaft end part 63 is connected to the end of the adjacent hollow shaft 55 by means of a tongue and groove connection 69 (FIG. 2). A drive shaft part 71 is connected to the top end of the hollow shaft 55 of the top washer arm 57, which drive shaft part is rotatably engaged with the hollow shaft 55 via a tongue and groove connection 69 (FIG. 2) as well. If the assembly 25 is installed in the filter housing 1, the drive shaft part 71 is rotatably mounted in the bearing point 17 of the housing cover 15, wherein a shaft ring 73 is also provided for sealing purposes. A cover part each is provided as the top and bottom end of the stacked structure of the filter inserts 27 75, which cover parts are identical parts and injection molded from plastic and which, after the insertion of the backwash device in conjunction with the hollow shaft end part 63 and drive shaft part 71, are glued to the respective facing annular bodies 29, 31. The cover parts 75 have spoke-like supports 77, extending from an inner hub 76 to an outer ring 78 located on the cover circumference, which leave fluid passages open between each other. One annular groove 79 for a sealing ring 80 is formed in every outer ring 78.

FIG. 1 shows the first exemplary embodiment having a backwash filter assembly 25 installed in the filter housing 1 where the stacked structure is formed of two filter inserts 27. To drive the backwasher arms 57, an electrically or hydraulically actuated drive motor 82 is connected to the drive shaft part 71 via a coupling part 81 located thereon. In the exemplary embodiment of FIG. 1, in addition to the backwash filter assembly 25 having the stacked structure formed from the two filter inserts 27, a stacked structure formed having an additional filter insert 83 is provided. This filter insert 83 contains a bypass device 84. The housing of this filter insert 83 has a bottom annular disk 85 and a top annular disk 86 on its two face sides, of which the bottom annular disk 85 is mounted on the top annular body 29 of the adjacent filter insert 27 using the same tongue and groove connection as is provided between the filter inserts 27 to form the stacked structure to which the filter insert 83 has been added. In contrast to the image in FIG. 2, the cover part 75 is mounted on the top annular disk 86 of the bypass filter insert 83. On the radially inner ends of the annular disks 85, 86, which are radially spaced from the drive shaft part 71, there are projections 87 projecting axially towards each other, which form the valve seat for the closing bodies 88 of a ring of bypass valves, which are pre-stressed in the closed position by means of springs 89. A filter material 91 forming the external circumference of the bypass filter insert 83 and extending between the bottom and the top annular disk 85, 86 forms a protective strainer when the bypass device 84 is activated.

During operation, the unfiltered fluid supplied via the inlet 11 flows through the passages between the supports 77 of the bottom cover part 75 into the interior of the filter inserts 27 and flows through the filter medium 43 during the filtering operation to the filtered fluid chamber 21 and is discharged through the outlet 19. The seal between the dirty side, i.e., the unfiltered fluid chamber 9 on the base 5, the interior of the filter inserts 27 and the central chamber 90 of the bypass filter insert 83 connected thereto, and the clean side, i.e., the chamber 21, is formed by the sealing rings 80 at the bottom cover part 75 and at the top cover part 75. During backwashing, which is performed with a backwash outlet 65 opened by means of a (not depicted) valve device, the slot nozzles 61 of the backwasher arm 57 move at small intervals along the inner frame parts 33 of the filter inserts 27, cf. FIGS. 5 and 6, in which FIG. 5 shows one washer arm 57 and FIG. 6 shows the other of the two washer arms 57 in a position taken at the same time. As can be seen from these figures, the opening of the one slot nozzle 61 is aligned with an inner frame part 33, when the slot nozzle 61 of the other washer arm 57 is aligned with an inner fluid passage point 37. In this arrangement the backwash operation runs essentially continuously, i.e. without significant pulsation of the backwash flow. At the same time, the volume of the backwash flow is limited because at any point of time the full passage cross section of only one fluid passage point 37 is available. As FIGS. 5 and 6 further show, the inner frame parts 37 have an oblique position relative to the radial direction, resulting in the flow direction of the flow through the passage points 37 being angled relative to the flow direction at the opening of the slot nozzle 61. This results in a flow direction in the chamber 41 during the backflow, as indicated in FIG. 6 by the dot-dashed line 62, in which the broad sides of the folds of the filter medium 43 are flowed through to facilitate the cleaning during the backwashing. The volume of the backwash flow is generated by the operating pressure of the system, for example an oil pressure in the range from 8 to 10 bar in a lubricating oil system. The backwash operation can additionally be supported by the generation of a vacuum at the backwash outlet 65. The fluid path inside the backwasher arms 57 expands relative to the opening cross section at the slot nozzle 61, which results in a type of Venturi effect and the flow rate in the immediate vicinity of the slot nozzle 61 is increased, facilitating the removal of contamination. If the filter medium 43 of the filter inserts 27 is blocked and the bypass device is activated, fluid reaches the filtered fluid chamber 21 and thus the outlet 19 through a filter material 91 forming a circumferential cylinder jacket between the bottom annular disk 85 and the top annular disk 86 and serving as a protective strainer.

The second exemplary embodiment of FIG. 7 differs from the first exemplary embodiment only by a different design of an additional bypass filter insert 93. In a manner similar to that of the filter inserts 27, the bypass filter insert 93 has a housing having a top, annular body 94 on the face side, on which the cover part 75 is mounted.

The filter medium 43 is arranged in a hollow cylindrical form between the inner and outer frame parts, as for the filter inserts 27, wherein the filter fineness for this filter medium 43, which serves as a protective filter, is not as fine as for the filter inserts 27 and is up to 100 μm. A perforated disk 96 is attached to the bottom annular body 95 of the bypass filter insert 93 to form the stacked structure with the annular body 29 of the filter insert 27 below. Said perforated disk is sealed by means of a sealing ring 97 on the drive shaft part 71 and has passages 98, on which valve seats are formed for the closing bodies 88 of a ring of bypass valves arranged vertically. If the filter medium 43 of the filter inserts 27 is blocked and the closing bodies 88 are opened, unfiltered fluid reaches the interior of the bypass filter insert 93 by means of the passages 98, exits via the filter medium 43 of the protective filter and reaches the outlet 19 via the chamber 21. The filter medium 43 of the filter inserts 27 can also have a coalescing layer in addition to the filter layer located between the outer support layers. 

1. A filter device, in particular for the filtration of lubricating oil, consisting of at least two filter inserts (27), in each of which a filter material (43) is disposed, which are provided with fluid passage points (37, 39) and which can be stacked on top of one another, thereby forming a stacked structure, and comprising a backwash device (55, 57), which is displaceably arranged along the inside of the filter inserts (27), characterized in that the individual filter inserts (27) are formed as identical parts at least with respect to their housing.
 2. The filter device according to claim 1, characterized in that the housing of the filter inserts (27) has an annular body (29, 31) on each free face side.
 3. The filter device according to claim 1, characterized in that at least one projecting annular rib (49) is provided on the annular body (29) on the one free face side of a filter insert (27), which projecting annular rib engages with an associated annular recess (51) in the annular body (31) on the other face side of a downstream filter insert (27), thereby forming the stacked structure.
 4. The filter device according to claim 1, characterized in that the relevant annular rib is sub-divided into rib parts (49) by means of at least one interruption forming a gap (47) and in that at least one projection (53) engaging with a gap (47) of the annular rib (49) is provided in the annular recess (51) of the downstream filter insert (27) in the stacked structure.
 5. The filter device according to claim 1, characterized in that the face sides of the filter inserts (27) facing away from each other arranged in the stacked structure each have a cover part (75), said cover parts being designed as identical parts.
 6. The filter device according to claim 1, characterized in that at least one part of the cover parts (75) is kept fluid-permeable.
 7. The filter device according to claim 1, characterized in that the annular bodies (29, 31) of the housing of the filter inserts (27), one of which has the annular recess (51) and the other of which has the rib parts (49), are connected to each other by means of inner and outer longitudinally extending frame parts (33, 35), which delimit between them window-like fluid passage points (37, 39), and in that a filter medium (43) is accommodated in the space (41) between inner (33) and outer frame parts (35).
 8. The filter device according to claim 1, characterized in that the backwash device has a motor-drivable backwasher arm (57) for every filter insert (27) which, formed in the manner of a slot nozzle (61), travels along the fluid passage points (37) formed on the inner frame parts (33) by means of a drive shaft (55) which, formed hollow, serves to remove backwash volumes from the device.
 9. The filter device according to claim 1, characterized in that the individual slot nozzles (61) are axially offset relative to one another and by a rotation angle such that at least one slot nozzle (61) is located above a window-like fluid passage point (37) and at least one additional, preferably adjacent slot nozzle is simultaneously disposed over a frame part (33) next to another passage point (37).
 10. The filter device according to claim 1, characterized in that the adjacent inner longitudinal frame parts (33) are slanted relative to the radial direction, such that they define a flow direction for every passage point (37) of each filter insert (27), which is slanted by a specified angle relative to the inflow direction of the opening of the relevant slot nozzle (61).
 11. The filter device according to claim 1, characterized in that the relevant slot nozzle (61) extends from the inner side of the assignable filter insert (27) towards the hollow drive shaft (55).
 12. The filter device according to claim 1, characterized in that the backwasher arm (57) for each filter insert (27) consists of identical components, which are connected to each other by a tongue and groove connection (69) at their face sides, comparable to that of the filter inserts (27).
 13. The filter device according to claim 1, characterized in that at least one spring-loaded bypass valve (84) is used as an additional filter insert (83; 93) in the layer structure.
 14. The filter device according to claim 1, characterized in that at least all filter inserts (27) are glued to one another at their adjacent face sides, thereby forming the layer structure.
 15. The filter device according to claim 1, characterized in that the layer structure having the filter inserts (27) can be removably installed in a filter housing (1), which has a fluid inlet (11) for unfiltered fluid, a fluid outlet (19) for filtered fluid and an outlet (65) for the backwash. 